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M oldings enhance the appearance of furniture and architectural millwork with their ability to catch light and make shadows. Most moldings are a combination of beads (convex curves) and coves (concave curves). Large coves are most often made with a shaper, but shaper blades are expensive, especially when they have to be custom ground-not to mention the cost of shapers themselves. So for short runs of molding or for shops that don't have shapers, tablesawn coves are a surprisingly versatile alternative. This article explains how to make a variety of coves using your tablesaw and examines ways of simplifying the usual trial-and-error set-up process. Safety issues raised by tablesaw coving are discussed in the box on p. 84. There are two main types of coves: symmetrical and asymmet- rical. Symmetrical coves, the more familiar kind, are cut by changing the angle of approach to the blade while leaving the blade perpendicular to the table. The stock rides along a skewed fence and passes over the top of the blade, removing an elliptical arc of wood, as shown in the bottom photo at right. Asymmetrical coves are cut by changing the angle of the blade's tilt as well as the angle of approach. This type of coving yields logarithmic, or accelerated, curves as shown in figure 2 on p. 85. Partial coves can be cut using special fence setups, such as the one shown in the photo on p. 85. Sy Symmetrical tablesawn coves are often used to approximate arcs of circles, but with one exception, they are actually sections of ellipses. As figure 1 shows, skewing the fence slightly from the normal ripping position produces a steep-sided elliptical cove; then, as the angle of approach is increased, the ellipse broadens and flattens out until, at 90° from the normal angle of approach, tl1e cove is an arc of a true circle. Because there are only two factors to contend with, the height of the blade and the angle of approach, setting up for symmetrical coving is not too complicated. mmetrical coves Symmetrical coves are cut with the blade vertical. Klausz shaves the last molding. The fence is set up to the infeed side of the blade, so the cutting action holds the stock against the fence. Setting up-It'S best to start by drawing the cove full size on the end of one of the pieces of stock you'll be cutting. Then you can make an accurate setup directly from the drawing of the cove. The height of the blade determines the depth of the cove, so butt the end of the piece up to the blade, and raise the blade to the highest point of the drawn cove. Next you need to find the correct angle of approach, and clamp a fence to the saw table. An easy way to find the angle of approach is with an adjustable parallelogram like the shop made one in the top photo. Flat-head machine screws work well at the joints. Countersink the heads so that the parallelogram will lie flat on the tablesaw, and use wing nuts with them so that you can easily lock in particular settings. As long as opposite sides are equal lengths, the construction details are unimportant. Adjust the parallelogram, so its width is the same as the widest point of the cove. Then, with the saw unplugged, place the parallelogram on the saw table, so it surrounds the blade. Turn the parallelogram until it just nicks the front and back of the blade. With pencil or tape, make location marks on the saw table inside the leg of the parallelogram that is touching the front of the blade. Measure back from your marks to account for the distance between the start Bringing out the shaper in his tablesaw, the author combines an angled fence and tilted blade to cut an asymmetrical cove for a piece of crown molding. From right, the coved pieces arrayed on the outfeed table are an asymmetrical cove and slices cut from it after every second pass, a symmetrical cove in a section of architectural molding, and two partial coves for an ogee bracket foot. Drawings: Maria Meleschnig Fig. 1: lf16 Temporary fence Symmetrical coves Blade remains perpendicular to table and cuts a symmetrical section of an ellipse. 0° blade tilt, 20° approach angle in. from a piece of symmetrically coved cornice Klausz finds the angle of approach for a symmetrical cove with a parallelogram set to the cove's width. With the blade raised to match the cove's highest pOint and the parallelogram just touching the blade at front and back, he marks the front fence location. Direction of feed 0° blade tilt, 45° approach angle -""1 I I 70° 0° blade tilt, 70° approach angle September/October 1993 83